<template>
    <div style="height:40px">
        <canvas id="canvas" width="100%" height="100%" class="codeImg" title="看不清，换一张"></canvas>
    </div>
</template>

<script>
export default {
    //将模块引出，在其他地方使用
	name: 'verCode',
    props: {
		randomString: { type: String, required: true }, // 随机字符串
    },
    data () {
        return {

        }
    },
    watch: {
        randomString() {
			this.drawPic(this.randomString);
		},
    },
    created () {

    },
    mounted () {
        this.drawPic(this.randomString);
    },
    methods: {
        /**生成一个随机数**/
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min);
        },
        /**生成一个随机色**/
        randomColor(min, max) {
            var r = this.randomNum(min, max);
            var g = this.randomNum(min, max);
            var b = this.randomNum(min, max);
            return `rgb(${r},${g},${b})`;
        },

        /**绘制验证码图片**/
        drawPic(num) {
            var canvas = document.querySelector('#canvas');
            var width = canvas.width;
            var height = canvas.height;
            var ctx = canvas.getContext('2d');
            ctx.textBaseline = 'bottom';

            /**绘制背景色**/
            ctx.fillStyle = this.randomColor(180, 240); //颜色若太深可能导致看不清
            ctx.fillRect(0, 0, width, height);
            /**绘制文字**/

            var txt = num;
            ctx.fillStyle = this.randomColor(50, 160); //随机生成字体颜色
            ctx.font = this.randomNum(25, 35) + 'px SimHei'; //随机生成字体大小
            var x = 1;
            var y = 60;
            var deg = this.randomNum(10, 8);
            //修改坐标原点和旋转角度
            ctx.translate(x, y);
            ctx.rotate(deg * Math.PI / 180);
            ctx.fillText(txt, 0, 0);
            // //恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180);
            ctx.translate(-x, -y);
            /* } */
            /* /**绘制干扰线**/
            for (let i = 0; i < 8; i++) {
                ctx.strokeStyle = this.randomColor(40, 180);
                ctx.beginPath();
                ctx.moveTo(this.randomNum(0, width), this.randomNum(0, height));
                ctx.lineTo(this.randomNum(0, width), this.randomNum(0, height));
                ctx.stroke();
            }
            /**绘制干扰点**/
            for (let i = 0; i < 100; i++) {
                ctx.fillStyle = this.randomColor(0, 255);
                ctx.beginPath();
                ctx.arc(this.randomNum(0, width), this.randomNum(0, height), 1, 0, 2 * Math.PI);
                ctx.fill();
            }
        }
    }
}
</script>

<style scoped lang="less">
.codeImg{
    width: 100%;
    height: 100%;
}
</style>
